Retina (@2x) image loading about nimbus

[jverkoey]

Do you mean loading retina images from disk? I think I may have overlooked this. The disk loader doesn't check for @2x prefixes on retina devices. This is trivial to add though, so if someone doesn't beat me to it I can get this fixed this week.

• Jeff

On 2011-07-17, at 3:58 PM, [email protected] wrote:

Looking through the network image sources, I'm trying to figure out if there's already a mechanism to handle retina image scales. I got excited when I saw the scale parameters, but it looks like it's for something else, related to aspect ratios.

Is there anything special that needs to happen in order to load retina images vs. standard images when available (and the device is retina capable)?

Reply to this email directly or view it on GitHub:
#16

[grgcombs]

Yeah ... Let's say I know I'm running on an iPhone 4 and have a retina display ... I could request @2x files from the server (maybe the lib would catch file not found from the response, drop the @2x appendage, and resend the file request automatically). Then set up the UIImage scale property accordingly based on what it found.

g

Sent from my iPad

On Jul 17, 2011, at 4:42 PM, [email protected] wrote:

Do you mean loading retina images from disk? I think I may have overlooked this. The disk loader doesn't check for @2x prefixes on retina devices. This is trivial to add though, so if someone doesn't beat me to it I can get this fixed this week.

• Jeff

On 2011-07-17, at 3:58 PM, [email protected] wrote:

Looking through the network image sources, I'm trying to figure out if there's already a mechanism to handle retina image scales. I got excited when I saw the scale parameters, but it looks like it's for something else, related to aspect ratios.

Is there anything special that needs to happen in order to load retina images vs. standard images when available (and the device is retina capable)?

Reply to this email directly or view it on GitHub:
#16

Reply to this email directly or view it on GitHub:
#16 (comment)

[jverkoey]

Ah, I see.

The way the network image view works right now, it works best for retina displays when you request images that are too large and must be scaled down. The scaling code you've probably seen here:

https://github.com/jverkoey/nimbus/blob/master/src/networkimage/src/NIHTTPImageRequest.m#L401

will create a higher resolution image from the source image on retina displays.

For example, say I'm loading a 500x500 image from the network and displaying it in a 100x100 image. On a non-retina display, the resulting image would be 100x100, but on a retina display the image would be 200x200 with a scale of 2.0.

From the sounds of it, this doesn't solve your particular use case, where you'd like to fetch a pre-created @2x image from the network. This is an interesting feature request. Given the intended use case for the network image view, I think that searching for the @2x file would be an optional feature that would be off by default, but I wouldn't be against adding it at all.

[grgcombs]

Cool!

[cuu]

I meet the similar problem
NIPhotoScrollView got problem with retina screen, the image in PhotoScrollView is smaller than in the same of iphone screen without retina.

so

• (void)minAndMaxScaleForDimensions: (CGSize)dimensions
  boundsSize: (CGSize)boundsSize
  photoSize: (NIPhotoScrollViewPhotoSize)photoSize
  minScale: (CGFloat *)pMinScale
  maxScale: (CGFloat *)pMaxScale {
  NIDASSERT(nil != pMinScale);
  NIDASSERT(nil != pMaxScale);
  if (nil == pMinScale
  || nil == pMaxScale) {
  return;
  }

  CGFloat minScale = [self scaleForSize: dimensions
  boundsSize: boundsSize
  useMinimalScale: YES];

  // On high resolution screens we have double the pixel density, so we will be seeing
  // every pixel if we limit the maximum zoom scale to 0.5.
  // If the photo size is unknown, it's likely that we're showing the loading image and
  // don't want to shrink it down with the zoom because it should be a scaled image.

  CGFloat maxScale = ((NIPhotoScrollViewPhotoSizeUnknown == photoSize)
  ? 1
  : (1.0f * NIScreenScale()));

I changed to (1.0f * NIScreenScale())); from (1.0f / NIScreenScale()));

Hope this can be helpful